Explosive drill



Feb. 17, 1953 R. J ASSE EXPLOSIVE DRILL 2 Sl-IEETS-SHEET 1 Filed Feb. 12, 1946 Arry':

Feb. 17, 1953 JASSE 2,628,559

EXPLOSIVE DRILL Filed Feb. 12, 1946 2 SK-IEETS-SHEET 2 Patented Feb. 17, 1953 EXPLOSIVE DRILL Raymond Jasse, Paris, France, asslgnor to Societe dite: Centre dEtudes, M. B. A., Paris, France Application February 12, 1946, Serial No. 647,069

In FranceFebl-uary 6, 1945 Section 1, Public Law 690, August 8, .1946 Patent expires February 6, 1965 2 Claims. 1

This invention has for its objectan explosive drill or perforator. which is of general use for boring operations, demolitions, destructions and parcelling operations and is more particularly intended for usein boring a deep hole in a predetermined direction in any natural or artificial obstacle.

According to certain features of the invention, theimproved perforator comprises a casing having a longitudinal. axis of symmetry, made of a light material such as cardboard or. sheet metal, and housing from rear to front at. least. one

priming charge in contact by a relatively wide.

surface with a main explosive charge provided with a cavity or recess flaring towardsthe front end'of the casing, a fixation devicebeing. secured to saidfront end in order tomaintain a predetermedspacingbetween the fore plane of said cavity and the surface of the obstacle to be bored.

Other features of the invention will appear from the following description.

In the accompanying drawings given by way of example:

Fig. 1 is a longitudinal section of the device,

Fig. 2 is a similar view of a modified construction.

Figs. 3 and 4 Show diagrammatically other arrangements of the charges.

In the, example shown in Fig. 1.,the drillor perforator comprises a cylindrical, container or casing l of cardboard or metal closed at its rear endbya woodenlplugl securedin the container by meansofscrews 3. The frontor inner surface of. saidrplug which isa surfaceofrevolutioncoaxial with the casing comprises a central spherical part ,4 and a flaring conical part 5. In'front ofgthe plug, the casingcontainsa primingcharge l madegof an explosive material piled up,,cast or highly compressed. Said charge is: contained in the bottom of the plug and is terminated at the front by a cross plane surface 8 of a comparatively great area. A blasting charge H1 is placed in front of said priming charge, the front surface of the same being a sphero-conical flaring surface coaxial with the casing and having a shape similar to thefront faceof the plug. The thickness of the composite charge in a direction parallel to the axis ofthe-casing is substantially uniform at all points of its cross section.

The container I carries at its front end a tubular extension open at both ends which is provided at its front endwith attaching means such as a bracket .12 by means, of which it may be readily secured to the obstacle l3 to be bored, as for instance by a nail M.

When. a. perforating operation is to be made. the casing is fixed to the obstacle so that its axis coincides with the direction of the bore to be drilled and a combineddetonator and fuze I5 is inserted through a hole provided axially in the rear end of plug 2 so as to contact with the priming or firing charge I. The shot is then fired.

The initial impulsion imparted by the detona tor fuze' I5 is transmitted from the rear tothe front first to the priming charge I and then to the explosivecharge Ill. The detonation is propagated frontwards by a decomposition of the main charge in successive layers having a shape correspondingsubstantially to the shape initially given to the rear part of said charge. In this manner the explosive waves are directed and concentrated towards a point located ahead somewhere on the axis of the casing, i. e. on the axis of perforation. By this means a maximum concentration of the explosive wavesis obtained in the desired direction with a minimum weight of explosive material. The device has thus a high eliciency.

Thecasing being made of a light material can be easily manufactured atreduced costs. The device is not heavy and can beeasily manipulated and it ensures a very small projection of inoffensivesplinters.

The length of the tubular extension II is so calculated that when the device is in firing position the front face of the. whole pyrotechnical body will be located ata distance'from the obstacle corresponding to the maximum. efficiency. Said distance, which varies according to the shape of the charges and the material constituting the obstacle is in all cases less than 1.5 the diameter of the charge. By merely placing the front end of the extension in contact with the obstacIe the device will thus be used in the best conditions.

Instead of the, shape described above,- the front faces of the plug, priming charge and blasting chargemay havethe shape of other surfaces of revolution of a conoidalcharacter suohasa paraboloid, an ellipsoid, etc; as showntin Fig. 2.

In this case, instead ofbeing plane, the contactsurface between the priming. charge and the.

blastingcharge has sucha shapethat the priming charge will partly envelop the blasting charge.

Such an arrangement'is of peculiar advantage, when the blastingspeed of the priming charge is higher than that of themain charge. Firstlyit ensures a substantially simultaneous lighting at all points of the contact surface between the priming charge and the main charge, so that the.

detonation waves when passing from the priming charge to the blasting charge.

In this manner the efficiency of the perforator is increased due to a better concentration of the blasting effect in the axial direction of the device.

claim as new and In some cases, it may be desirable to adjust with a greater accuracy the direction of theaxis of perforation. For this purpose, the device is completed by a funnel shaped hollow member 18 I (Fig. 2) having removably and telescopically engaged in the free end of the casing I. A short hole [9 having a small diameter is drilled in the face of the obstacle or structure to be bored. In operation, the reduced end or nozzle of said funnel member 18 is introduced into said hole. The device is thus given at once a correct position in which it is properly secured on'the obstacle or structure to be drilled. r

The construction may be so devised that for storing and handling purposes the funnel will be placed inside the casin extension in an inverted position, as shown in dotted lines in the lower part of Fig. 2. The bulk'of the whole device is thus reduced and the funnel acts as a protective covering for the front end of the same.

The plug 2 may be composed of separate pieces of wood or cardboard or by a body of an inert material such as earth or kieselguh'r, which will not become agglomerated or solidified under physical or chemical actions (shocks, heat, etc.)

Said body is held at the rear'end of the casing by an end wall 29, as shown in Fig. 2. In said figure, the casing is madeof sheet metal.

Fig. 3 shows another modification in which a plurality of priming charges is provided." In said figure, the blasting charge 20 is partly enveloped by a priming charge 21 which is' itself partly enveloped by a priming charge 22 at the topof which is provided a recess 23 for housing the detonator fuse. The shape of the charges is of the type described with reference to Fig. 2'. As shown approximately in Fig. 3, the solid angle at the apex of each charge gradually increases from one charge to the next, from the rear end to the front end of the device. materials constituting the various charges are chosen of different grades or are compressed diiferently one from another so that the detonation speed in the charges will progressively decrease from the rear end to the front end of the device.

In this manner, the concentration of the detonation waves along the axis of the device will progressively increase from the first priming charge 22 which is fired directly by the detonator fuse to the second priming charge 2| and then'to the blasting charge 20, which will increase the efiiciency of the device.

Fig. 4 shows a further modification in which recesses 25, 2t, 21 are formed in the outer face of the second priming charge 21, which may be considered as an intermediary priming charge or an orientation charge. Said recesses are so arranged that their axial lines such as a, b, 0 will converge to a point :1 located on the axial lineof the casing, whichds also the axis of the;reces s, or cavity formed by the outer face 1 of the blast- Moreover the explosive ing charge. By providing such recesses, the con-- centration of the blasting waves along the casing axis is further increased. Said recesses could be bodies of revolution and have an annular or toroidal shape.

The whole of the priming and blasting charges can be wrapped in a light envelope made of paper, cardboard or metal, according to the shape and nature of the constituents of the charges, so that they may be introduced more easily into the casing.

Having now described my invention what I desire to secure by Letters Patent is:

1. In an explosive drill having an outer casing having .afbase portion closing one end thereof whilst the other end is open and free and a drill I hollow charge in said casing adjacent said base portion, means for securing said drill to the structure to be drilled comprising a sleeve engaging the free open end of the casing, a substantially funnel-shaped member attached to the outer end of said sleeve, said member terminating in a tube adapted to enter a hole of small diameter in the structure tosupport the drill on the structure.

2. In an explosive drill having an outer cas ing having a base portion closing one end thereof whilst the other end is open and free and a drilling hollow charge in said casing adjacent said base portion, means for securing said drill to the structure to be drilled comprising a sleeve, engaging the free open end of the casing, a conical member secured to the free end of the sleeve and an elongated tube secured to the reduced end of the conical member, the tube being adapted for insertion into a hole of small diameter provided in the structure to b drilled to secure said drill in the structure.

' RAYMOND JASSE.

REFERENCES CITED The following references are of record in the file of this patentzj UNITED STATES PATENTS Number Name Date 356,064 France Jan. 11, 1887 1,029,051 Dutcher June 11, 1912 1,088,606 McGinley Feb. 24, 1914 1,406,844 Gelm Feb. 14, 1922 1,440,601 I-Iolran Jan. 2, 1923 1,531,555 Harris et'al. Mar.31, 1925 1,534,011 Watson Apr. 14, 1925 1,534,012 Watson Apr. 14, 1925 2,247,169 'Gilbertson" June 24,1941 2,407,093 Mohaupt Sept. 3,1946 2,419,414 Mohaupt Apr. 22, 1947 2,420,201 Seavey May 6, 1947 ISQREIGN PATENTS Number Country f Date 20,110 Great Britain of'1911 28,030 Great Britain 1911 113,685 Australia Aug. 1941 OTHER REFERENCES Zeitschriit' Fur D'as Ge samte Schiess und Sprengstoffwesen, pages 183 187, Article by E. N. Darmstadt (May 15, 1914)." l

The Illustrated LondonNews .(Nov. 25, 1944), The Hollow Charge'f. pages 6047605.

The ExplosivesEngineer (July-August 1945), Article by Volta Torrey, pages -1-63. 

